I wouldn't have a problem with AROS or Anubis, or even MorphOS or OS4 on these machines. Otherwise, don't call it "Amiga."
You can install AROS on any x86 for free... that means you'll be able to install it on future Amigas as well.
When C=USA originally announced their intentions of developing AROS, I was strictly against it. It is a dead platform, as any other AmigaOID around. You'd have to pour dozens of millions of dollars into it to even have a remote chance of being succesful in mainstream. In doing so, you would introduce things that were never present in the original AOS, like memory protection, which means several things... first, it would loose some of it responsiveness because of that and secondly, it would basically become a new OS with very few connections whatsoever to the original. It would loose probably most of it Amiga-like features in the process... It simply doesn't make any sense next to a perfectly working kernel like Linux + GNU tools.
Original AmigaOS and it's derivatives are a dead platform(but they remain a nice hobby OS). It was helluva OS back in it's days, but by 1990s even people in Commodore were perfectly aware of it's faults. That's why several other options were considered even back then and that's why Gateway wanted QNX/Linux in 1999.